This invention relates to a two-sided printing machine which is compact and in which sheets can be readily gripped in a series of printing steps from a sheet feeding step to a sheet discharging step.
In a conventional two-sided printing machine, as shown in FIG. 1, a sheet is conveyed from a sheet feeding section A' through a sheet conveying mechanism B' to a sheet inserting section C'. Then, the sheet is placed between a rubber blanket cylinder 102 and a blanket cylinder 103. Plate cylinders 101 and 104 are inked by inking devices E' and F'. Therefore, the patterns on the plate cylinders are transferred to the blanket cylinders 102 and 103, so that the sheet is subjected to two-sided printing. The sheet thus printed at station H' is delivered out by a chain delivery section D'.
In the conventional two-sided printing machine, the sheet inserting section C' is near the blanket cylinder 103. This is shown schematically in FIG. 1. Also, a gripping mechanism in the chain delivery section, adapted to grip a printed sheet delivered from the impression cylinder 103, is provided near and downstream of the blanket cylinder 103. Therefore, it is rather difficult to clean the blanket cylinders and to replace the blanket on the blanket cylinder 103. Furthermore, in a series of printing steps, a sheet is gripped twice, that is, when the sheet is transferred from the sheet inserting section C' to the blanket cylinder and when it is transferred from the blanket cylinder to the chain delivery section D'. There are gaps in the handling of the sheet in a positive manner as the printing steps are performed.
Accordingly, operations for stabilizing the flow of sheets from the sheet feeding section to the sheet delivery section are intricate, and the length of the entire machine is therefore necessarily large. In these respects, the conventional two-sided printing machine is disadvantageous.